NS for FX: add test for a simple sparsenn model (#52092)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52092
Adds a very simple toy sparsenn model, and enables
its inspection with the new NS APIs.
Test Plan:
```
python test/test_quantization.py TestFXNumericSuiteCoreAPIs.test_sparsenn_compare_activations
python test/test_quantization.py TestFXNumericSuiteCoreAPIs.test_sparsenn_shadow
```
Imported from OSS
Reviewed By: raghuramank100
Differential Revision: D26403095
fbshipit-source-id: 3c3650aca47186deb32f2b3f1d87a0716d1ad9d1
